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Full text of "Tests of insecticides for control of the pickleworm and associated insects on cucumbers and squash, 1948-51"

LilLJlxr-viv x 



TATE PLANT BOARD 

May 1953 E-856 

United States Department of Agriculture 

Agricultural Research Administration 

Bureau of Entomology and Plant Quarantine 



TESTS OF INSECTICIDES FOR CONTROL OF THE PICKLEWORM 
AND ASSOCIATED INSECTS ON CUCUMBERS AND SQUASH- -1948-51 

By W. J. Reid, Jr., and F. P. Cuthbert, Jr. . 

Division of Truck Crop and Garden Insect Investigations^-' 



The pickleworm ( Diaphania nitidalis (Stoll)) is a serious pest of 
cucurbit crops in the South Atlantic and Gulf States. It frequently causes 
considerable damage in adjoining States, and occasionally occurs as far 
west as Texas, Kansas, Missouri, and Iowa, and as far north as the 
tier of States extending from Illinois eastward to Connecticut, including 
New York. Summer squash is its favorite host, but it often severely 
damages cucumber and muskmelon. Occasionally young tender fruit of 
winter squash is attacked. The pickleworm is active throughout the 
winter in the extreme southern part of Florida, where its cultivated or 
native hosts are available continuously. From this and similar sub- 
tropical areas the insect gradually spreads northward each year, and 
usually appears later in the spring than most insects. Evidently it 
does not survive the winter as far north as the Carolinas. 

The melonworm ( Diaphania hyalinata (L.)), a species related to but 
less destructive and more easily controlled than the pickleworm, has 
about the same distribution in the United States. In addition, it has been 
reported from Arizona, New Mexico, and southern California, and 
adults have been taken in Canada. Apparently it also overwinters only 
in semitropical regions. 

The banded cucumber beetle ( Diabrotica balteata Lee.) and the 
spotted cucumber beetle ( Diabrotica undecimpunctata howardi Barber) 
often injure young cucumber plants, and the striped cucumber beetle 
( Acalymma vittata (F.)) damages the plants and fruits. The melon aphid 
( Aphis gossypii Glov.) often causes serious damage to cucumbers. 

Because of its habit of tunneling into the stalks, vines, buds, 
flowers, and fruit of cucurbits, the pickleworm has been difficult to 
control with the insecticides known prior to World War II. Studies con- 
ducted near Charleston, S. C, from 1930 through 1934 showed the need 
for more effective control measures. In 1948 these studies were re- 
sumed to determine the control value of some of the newly developed 



1/ In cooperation with the South Carolixia Agricultural ExDeriment 
Station. 






h •■ , phytol ments made to learn 

th< ■ owth < umber plar.- , 

is anei s on the effect of 

lind nt. All studies are being 

ntinued, urough the 1951 season is reported 

. 

R] I I.M KKAl I }. 

:nmendations for i . of the pickleworm prior to 1925 c( 

sist( • s. Q nee (16, 17), Smith ( 19, 20), 

( 21 ) advocated early planting, destruction of crop remnants, 
i use of > ip crop in cucumber and cantaloup planting 

Th« sidered ins* !es of little value. Quaintance and Smith did 

ie use of an arsenical spray to combat the melonworm. 
or rotenonc lining materials were among the most effec f 

discussions of • '-worm published between 1937 and 

194 , Arant l , . _i, and Fulton (_U). Fulton 

small ■ ■ , ite residue^ 

>lina wh- fruits we • ked S' 

He also obtained promising results wit! ;n 

He < red the use of squash as a trap crop to be of 

! the destruction of d- op remnants of no bene! 

eems first to express t ; hat the pickle- 

inters only in semitropi ^ions, where a continuous 

soi f food ble. Our findings ' ears substantiate 

. 
In inia by Bro \nders 

nd Hoi rH hlori^: 

Dl) l , md TDE (DDD) ] ■ • linst ■ n, but 

thai ui rtditiona BHC caused 

nijui ■;. nd cantaloup . ell 

hlorii 
inflicting inju . Alban and Keirns {I), 

I : ; (7), and M . , tests in Ohio, 

I Canada, 

l . 
. 

Duprei 

lane, parath Lon, pur DT, nd ci 

In the in this pub: [cation, nd 



3- 



Considerable toxicity of the fungicide zineb to the pickleworm and 
the melonworm was observed in Florida in 1949 by Genung (12) and in 
South Carolina in 1950 by Reid (18). Genung stated in correspondence 
that he obtained similar results in Florida in 1950. 

EARLY EXPERIMENTS 

Nine experiments, consisting of field-plot comparisons of several 
insecticides in the control of the pickleworm and the melonworm on 
summer squash, were conducted by the senior author near Charleston, 
S. C, during the fall-crop seasons of 1930 through 1934. Cucumbers 
and muskmelons were added in 1934, From three to eight, usually four, 
replications of each insecticide were made on plots from 5 to 16 feet in 
width (1, 3, or 4 rows) and from 120 to 262 feet in length. The plant 
varieties used were White Bush, Yellow Crookneck, and Cocozelle 
squash, Early Fortune cucumbers, and Hale's Best muskmelons. The 
insecticides were applied with a bellows-type knapsack duster early in 
the morning in 1930-33 and in the early part of the night in 1934. The 
number of applications ranged from 5 to 12, and the dosage from 12 to 
33 pounds per acre. An exception was a dosage of 54 pounds of a free- 
flowing lead arsenate-sulfur dust in one experiment. Applications usually 
were made every 3 or 4 days during the period of greatest insect abun- 
dance and every 7 to 10 days thereafter. Sometimes they were discon- 
tinued when fruiting began in order to avoid poisonous residues. 

The results of these early experiments were based chiefly on yields 
of sound and wormy (pickleworm-infested) fruits, supplemented by 
pickleworm and melonworm survival counts in 1934. 
The following insecticides were tested: 

Lead arsenate, calcium arsenate, and potassium hexafluo- 
aluminate, undiluted and diluted with 5 parts of sulfur, 
hydrated lime, or a copper-lime fungicide. 
Barium fluosilicate, diluted with 5 parts of hydrated lime in 
one test, and with 1 part of wheat flour and 4 parts of sulfur 
in another. 
Cryolite (natural, containing 89 percent of sodium fluoaluminate), 

diluted with 1 part talc and 3 parts of sulfur. 
Paris green, diluted with 4 l/2 parts each of hydrated lime and 

sulfur. 
Derris powder, diluted with sulfur and either talc or kaolin, 
sulfur composing one-third of the mixture, which contained 
various strengths of rotenone; in one test derris was diluted 
with tobacco dust to contain 1 percent of rotenone. 
Pyrethrum dust, two of unknown pyrethrin content and one 

diluted with tobacco dust to contain 0.1 percent of pyrethrin I. 



■ 



ntrol of the melonworm. 
' d that a 1-per- ,st ga -.o 

9'' ductioi , ■ none dus :.d 

undil nelonworm 

ilmost exclusively on platv not difficult 

■ v ith in • 

nan the melon- 
worm. Each of tt s of some value, but adequate con- 
! was <i when the ins* -> abur. I , lough 

:ons were made. sound fruit obtained from 

unti , no sound d squash being 

. untreated ; xperiments. from 

ur> >f the other • ments, during the peak of I le- 

: from cent of the squash produced. 

App ly during th< ;;ung stage of squash f 

ve; 55 percent of the fruits we i- 

sulfur dust were made at that til 
Lea , xafluoaluminate, and barium fluosi. 

effective against the p. . than ite 

I pari elds of sou; om pi. :.g 

most « * DiQit'izod bv th© Intornot ArGhiv^ cnau " si; 

— iluminate -sulfur, ■■■ < ■ '46 bushels per 

hough 1 jp '2013 ' u were infested in 

ated plants produced no squash. 
In th( in which it was used, a cryolite-talc-sulf 

dust ni' reased the yield of sound squash by 115 bushels per acre, "d 
only 2 .In the same i 

1 .5 • ind squash I 

, but 1 1 percent of th- 
nts in th. 

l ) 11 lequate conti 

• • ■ . • 

ns 

eighl app] 

len pr 
Ifur prov< 

I • 
■ 

http://archive.org/details/squashcuciciOOunit 



5- 



were diluted with sulfur than when used undiluted or mixed with hydrated 
lime or copper-lime. 

In general, the early studies indicated that (1) the pickleworm is 
more difficult to control than the melonworm, (2) pickleworm mortality 
counts are impractical after the insects begin tunneling into the plants 
and fruits, (3) for adequate control the pickleworm must be killed before 
this tunneling begins, (4) undusted barrier rows and check plots serve 
as sources of infestation of surrounding plants, and (5) more effective 
control measures and insecticides involving residues less hazardous 
than used previously are needed. 

PHYTOTOXICITY EXPERIMENTS 

The effect of the periodic use of several new insecticides on the 
growth of three varieties of cucumbers was determined in the experi- 
ments conducted in the spring of 1948 and 1949. Practically no insects 
were present on cucumbers during these experiments, and all yield 
differences are considered to be due to the direct effect of the insecti- 
cides on the plants. 

Each plot consisted of two rows 6 feet wide and 36.3 feet long. The 
plots were arranged in randomized blocks. Seven applications were 
made at weekly intervals in 1948 and eight in 1949, beginning about a 
week after the plants came up (when the second true leaves appeared) 
and ending the day of the third harvesting in 1948, and that of the first 
harvesting in 1949. The applications were made in the morning with 
rotary hand machines on wet to moist plants, with one or two trips per 
row. Dry plants were sprayed with water before being dusted. A cloth- 
covered hood with a plastic-cloth apron 8 or 10 feet long was often used 
to reduce insecticide drift. 

In 1948 from 8 to 19 pounds per acre were used in the first four 
dustings and from 20 to 37 pounds thereafter. In 1949 the dosage ranged 
from 12 to 20 pounds for the first five dustings and from 20 to 26 pounds 
thereafter. Nine harvestings at 2- to 3-day intervals were made each 
season. 

The yields of marketable cucumbers obtained during these experi- 
ments are summarized in table 1. 

In 1948 a BHC dust severely bleached and stunted the plants of each 
variety from the outset, and reduced the yield of the Marketer variety 
by 35 percent and that of S. C. 5 (a mildew-resistant breeding line) by 
69 percent. 

In 1949 an impregnated 1 -percent DDT dust made from a commercial 
dust that was stated to contain 10 percent of purified DDT (setting point 
103° C.) and 23 percent of an aromatic petroleum -derivative solvent 
significantly affected cucumber yields. It caused chlorosis and stunting 
of the plants from the outset, the injury being severe after the third 



-6 



Similar use of a dust • r 'ing only 2 percent of a com- 

mixture of di- and tri-methyl naphthalenes) on an 
outside row in the same cucumber planting apparently caused no inj\ 
to the- plants. Is of marketable Palmetto cucumbers, a recent, 

developed mildew-resistant var e reduced by 64 percent and 

se of the S.C. 5 breeding 1 63 percent. The purified, but not 

Impregnated, 3 -percent DDT dust caused slight chlorosis in some S.C. 5 

:its and moderate chlorosis in some Palmetto plants I third appli- 

I his inji. ,e less apparent as the plants grew, and there 

was no significant effect on yields. The 5-percent methoxychlor dust 
caused slight chlorosis in a few plants of each variety, but did not 
significantly affect the yields. 

One percent gamma BHC dusts, prepared from concentrates of 
approximately 95-percent gamma content, caused no visible plant inji: : 
and did not significantly affect yields in either year. The commercial 
product used in 1948 had little odor when diluted to a 1 -percent gamma 
dust; that used in 1949 had a slight odor. In 1948 plants of the Marketer 
variety getting the 1 -percent gamma dust gave slightly higher yields 
than untreated plants; the reverse was true of the S.C. 5 breeding line. 
1 he yields of dusted plants of both S.C. 5 and Palmetto cucumbers tended 
to be lower than those of plants not recei the gamma BHC dust in the 

spring of 1949, but the differences are not statistically significa . 
i.me was used when it became available in the fall of 1949. 

CONTROL EXPERIMENTS 

Thirteen field -pl( nts desig: • : • Lop a program for 

the control of the pickleworm and assoi I insecl - on the fall 

crop of cucumbers were conducted each year from 1948 through 1951. 
Tw<» c conducted on squash, one each in 1950 and li' 

1 ich m t was used on four to s. 

Id plots cons plants. The rows 

, av 1/20* 

in which ' ere ii T feet '. , . The dusts w 

in th< J as in tin 

(two or- thre< trips per row) w ■ ■ 

I 

i tely v. 

. _ g 

pp] ic<i, bul d hen th< 

i) D gall< 

the 

am 

applied at th< 



- 7 - 



The fungicides were applied about once a week, beginning about 10 days 
after seeding and ending 2 to 3 weeks before completion of harvest. 

The insecticide applications on cucumbers were made as shown in 
table 2. 

Control During Early Stages of Plant Growth 

Special efforts were made to find methods of evaluating the effec- 
tiveness of insecticides in pickleworm control before yield records 
could be obtained. Early-season control data were needed for com- 
parison of the more toxic materials, which should be used only during 
the prefruiting period of plant growth because of residue hazards. In 
the early experiments examination of squash plants from which yield 
data were to be secured did not prove feasible, because the plants had 
to be destroyed to find the larvae that had tunneled into them. The 
problem was even more complicated with cucumbers, because it was 
difficult to separate the plants after the vines became entangled. 
Examination of surplus plants at the time of thinning and of the staminate 
flowers later were possibilities explored in the fall seasons of 1948 and 
1949. 

The numbers of surviving insects on surplus plants at thinning time 
provided an indication of the effect of the insecticides on pickleworms, 
melonworms, and melon aphids. The information was limited, how- 
ever, by the small number of plants examined, the small size of the 
plants, the light infestation usually present at that time, and the few 
applications ordinarily made before thinning time. In spite of these 
factors, survival counts of the melonworm and melon aphid at this time 
seemed worth while. 

The number of pickleworms and melonworms (the former com- 
prising about 90 percent of the total) in the staminate flowers shortly 
before harvest was a reliable index to the effectiveness of the insecti- 
cides, being more closely correlated with yield data than counts made 
at thinning time. The pickleworm control in the flowers was usually 
higher than that obtained on the fruits. Control data based on flower 
examinations are limited, because ordinarily only small pickleworms 
feed in cucumber blossoms and many do not feed there at all. Squash 
flowers, however, are larger and larvae are able to complete develop- 
ment in them. Flower examinations made as near harvesttime as pos- 
sible should prove valuable, particularly in work with squash, if yield 
data cannot be obtained. 



' introl During Fr\n- 3 iges of Plant Growth 

PC based chiefly upon the pc 
:'ruits of all 1st , 1 1 • I . irm- 

( sound) of all sizes anc , the number (and sor: 

es weight) fruits, and the degree of 

nts. ft that showed a picklewor 

e hole was classed as wo . | rom 7 to 11, usually 9 or 10, 

stings were made. Fruits from all plants on each plot were picked 
I days. All cucumbers remaining on the plants were included 
in the last harvest. Where all marketable fruits were not weighed, the 
er required for a bushel was determined at least twice each season, 
lined from comparisons of the various insecticides are 
given in table 3, and those obtained from use of the more promising of 
these materials at various application intervals are shown in table 4. 

Effects of certain insecticides on a moderate melon aphid infestation 
that in plots of the 1951 pic kleworm-control experiments we 

ermined by picking 10 leaves at random from each plot and separating 
them into the following classes: Free (no aphids), slight (1 to 20 aphid 
moderate (21-100 aphids), and heavy (more than 100 aphids). al 

values wereassigned to th< Lous classes as follows: Free 0, slight 1, 

moderate 5, and heavy 20. The number of leaves occurring in each class 
was multiple the numerical value of the class, and the product was 

adc tjive the infestation rating of the plot (table 5). 

In the following discussions tl I ious insecticides are evaluate 

. on the basis of the percent of tl 1 number of fruits h ted 

that were wormy (pukleworm inf< Some cor. , 

1 sound fruits produced, as well as 
eld of marketable , in inst .11 

ded as having given adequate pickli control when the 

wormy fruits did nol total. Unless 

•s of the in^- 
mixtun eight basis. 

A . 

<). Y\: . .d not 

of th< : 

R 
[equate com 

Ith lind 
it i lldrin .'■ 

■ • • 



-9 



with aldrin in 1951 (table 5). This insecticide showed no phytotoxicity 
to cucumbers. 

Allethrin 

When applied directly on the insects in laboratory cage tests in 1950, 
a 0.5-percent allethrin dust proved toxic to third-instar pickleworms, 
but it was less effective against last-instar larvae, even when used at a 
heavy dosage. A 2-percent allethrin dust showed only moderate toxicity 
to last-instar pickleworms. The addition of 1 percent of piperonyl 
cyclonene and of compound 469 did not appreciably increase the toxicity 
of a 0.5-percent allethrin dust. 

In field plots a 1 -percent allethrin dust was of some value against a 
light pickleworm infestation in 1950, but was not of significant value 
when a moderate infestation prevailed in 1951 (table 3). Piperonyl 
butoxide, compound 469, and an activated nicotine did not appreciably 
increase the effectiveness of a 0.5-percent allethrin dust in 1951. 

BHC 

BHC caused serious injury to cucumbers in the spring of 1948 (table 1) 
and was not used in later tests. For tests with gamma BHC, see Lindane. 

Chlordane 

A 2 -percent chlordane dust had no apparent ill effect on cucumbers 
in the spring of 1948 (table 1),, but caused slight to moderate chlorosis 
of about one-third of the plants in the fall of that year. It was one of 
the least effective insecticides against the pickleworm in the fall of 1948 
(table 3). 

Cryolite 

Cryolite gave an intermediate degree of control of the pickleworm. 
It provided adequate protection against the melonworm and cucumber 
beetles, but apparently increased melon aphid populations on cucumbers. 
This aphid was more abundant on cryolite- treated plants than on plants 
receiving any of the other materials in two experiments each in 1948 
and 1949. In 1951 populations of this aphid were highly significantly 
greater on cryolite -treated cucumbers than on untreated plants (table 5). 

A cryolite dust of 50-percent sodium fluoaluminate content gave 
near-adequate control of a moderate pickleworm population when applied 
every 5 or 7 days in 1948, but not when applied every 10 days (table 4). 
Weekly applications in 1949 did not give satisfactory protection against 
a heavy infestation. When accompanied by zineb, a 70-percent cryolite 



10 



dust gave satis: >ntrol ght n .on in 1950 and near- 

I Of a m< te one in 1951 (tables 3 and 

. ed ir : to lindane and purified DDT and 

su{ • olite to cucumber or 

'i plants was ol I ->idue.^ ussed on page 



CS-674A, C " , I ( S-708 

J-674A proved superior I nilar material CS-645A in 1949, 

when a 2-percent dusts against a heavy infestation of the pickle- 

, hut these materials and a mixture of them known as CS-708 did 
not give adequate control (table 3). CS-645A was more effective in a 
spray than in a du: - . '. 5-percent CS-71 B dust gave adequate protection 
to cucumbers against a light infestation in 1950, but a 2-percent dust 
did not do so against a moderate infestation in 1951, being inferior to a 
0.5-percent lindane dust. Plants receiving CS-708 in 1951 had a higher 
melon aphid infestation than untreated plants . three 

materials showed no phytotoxic lty to cucumbers. 

DD I 

In the fall of 1948 a dusi containing 3 percent of a purified, or 

DDT (setting \ J°C.) caused no apparent injury to 

.< umbers; a similar strength of t- il DDT (setting point 9( C« 

dust caused slight to modei a'i i hlorosis i •-. Slight to 

moderate chlorosis of cucumbers, bul 'Id reduction, result 

m use of the p> : grad« 50. No difference in the degree of 

control of the pic kleworm affo .d purified grades 

nidi n the 1948 fall-season t le 3). 

purified gr-adt- A DDT ga\ ' 

Lnst tt. on worm and cucumber bed 

•cc of control of the pickli 

hlor. '. I 

in on cucuml and in 1 

not so lite, 

Lning : DD l 

pickli 
■ , -i, : :.• to 14 d 

■ 

| 



-11 - 



Residues at harvest after the use of DDT on cucumbers are discussed 
on page 17. 

Dieldrin 

In laboratory cage tests in 1950 a 2.5-percent dieldrin dust gave 
complete kill of third-instar pickleworms, but only 30-percent kill of 
last instars. In a field experiment this dust gave complete control of 
a light pickleworm infestation in 1950 and adequate control of a moderate 
infestation in 1951, being among the most effective materials and as 
toxic as a 1 -percent lindane dust (table 3). Dieldrin gave excellent 
control of the melon aphid in 1951 (table 5). It showed no phytotoxicity 
to cucumbers in 1950 and 1951. 

A 1 -percent endrin (the stereoisomer of dieldrin) dust was as effec- 
tive against the pickleworm and the melon aphid as a 2.5-percent dieldrin 
dust in 1951 (tables 3 and 5). Endrin caused slight to moderate burning 
and chlorosis of cucumber foliage. 

Heptachlor 

A 0.24-percent heptachlor spray (2 pounds of a 50-percent wettable 
powder to 50 gallons) gave good control of a light pickleworm infesta- 
tion in 1950, but a 2.5-percent dust did not prove very effective against 
a moderate infestation in 1951 (table 3), The dust apparently gave 
partial protection against the melon aphid (table 5). Heptachlor showed 
no phytotoxicity to cucumbers. 

Lindane (or gamma BHC) 

Lindane (or gamma BHC) was the most generally effective of the 
insecticides given extensive trials on cucumbers and squash. Good to 
excellent control of the pickleworm, as well as of the banded, spotted, 
and striped cucumber beetles, the melonworm, and the melon aphid, 
was obtained when a 1 -percent dust of either material was applied 
every 7 to 10 days at about 20 pounds per acre (tables 3, 4, and 5). 
Emulsion sprays containing 0.025 to 0.058 percent of lindane applied 
to give 0.125 to 0.250 pound of lindane per acre and a suspension spray 
containing 0.06 percent applied at the rate of 0.25 pound of lindane per 
acre also gave good control of these insects. In 1950 and 1951 weekly 
applications of a 0.5-percent lindane dust gave good control of the pickle- 
worm when accompanied by separate approximately weekly applications 
of zineb. 

Gamma BHC and lindane provided satisfactory insect control on 
several thousand acres of fall-crop cucumbers grown in the vicinity of 
Charleston, S. C, between 1948 and 1951. 



STATE 



- 12 



No pi md squash was observed, 

emulsion spray caused a slight chlorosis of small 
lants were not injured by later app. .as, 

arentlv v. d. A 1 -percent lindane dust 

: every 5 days somi ised sh^ht to moderate ir. 

esult f] ^sive : ts of any dust on cucumber foliage. 

Prelimil were made at three Locations betweer. 

out H3 , including men, women, and children, in 

••term. rj gamma BHC tl th< | 

ienced taste panels were not involved in the 
studies. Approximately 118 comparisons were made of lots of one to 
three cu ers from lindane- - .d untreated field plots. Prat - 

reate<: ; came from plants that received several 

applications of either a 1 -percent gamma dust or a spray containing 1 
pound of a wettable 25-percent gamma powder to each 100 gallons of 
wa , he last appli ueing m; ■■ samples 

harvested. Off-flavor or off-odor of one or more of the fruits in the 
ited lots was reported in 18 percent of the comparisons, but onl ;. 
few of them were said to be objectionable. Only two persons are known 
to have distinguished between all treated and untreated fruits. One of 
these persons has had considerable taste-panel experien* e. He stated 
that the off-flavor probably would not be . the averag> on. 

Lindane has been used extensively in re ••ars on commercial 

■ntings of fresh market cucumbei s in th< f Charleston, S. I . 

No complaints of an < Lonable odor or taste of the fruits have come 

to our ion. We understand that similar conditions ha\ ed 

in southeastern States. It is possible that off-fla .e 

use of lindane may be more pronounced when the cuci. -;ed 

when they are small, as usually is done I . 

Sir • toes grown Ln soil I ith Lindane 

, kpatri< -. et, al. i 

hethei 

I sufficiently ;uent 

I Of pol . In 1 

I • Lumph, l • I Jobblei , Sebago, and 

D fine sandy loam soil m whi< h 

the fall ol i he pickleworm had beei 

•al of I l/4 

app: .1 

: eld in whicl 

in • 

BHC it in no 



13 



undesirable. The results with Bliss Triumph were not clear-cut but 
showed a similar trend, whereas there was no significant off-flavor in 
the other two varieties. 

Insecticide residues on cucumber fruits following field applications 
of lindane and gamma BHC are discussed on page 17. 

Methoxychlor 

Methoxychlor proved to be one of the least effective materials against 
the pickleworm. Inadequate control resulted from the use of a 5-percent 
dust in 1948 (table 3) and in 1949 (table 4), a 2.5-percent impregnated 
dust in 1949 (table 3), a 10-percent dust in 1950 and 1951 (table 3), a 
0.181-percent suspension spray in 1949, and a 0.189-percent emulsion 
spray in 1949 (table 3). Methoxychlor was inferior to lindane in every 
comparison and usually proved inferior to cryolite. Methoxychlor was 
of considerable value in the control of the melonworm in 1948 and 1949 
(data not shown in tables). This material did not reduce the melon aphid 
infestation in 1951 (table 5), but on methoxychlor-treated plants the 
aphid population was lower than on plants receiving several other in- 
secticides and was no higher than that on untreated plants. Methoxy- 
chlor caused slight to moderate chlorosis of cucumber plants, but this 
injury did not appreciably affect yields. Methoxychlor residues are 
discussed on pa-ge 17. 

Nicotine 

Nicotine was used as an additive to control the melon aphid and to 
increase the degree of pickleworm control given by another insecticide. 
A cryolite-nicotine dust held the melon aphid in check in 1948 and 1949, 
but there was an increase in the infestation when cryolite was used alone. 
Nicotine was of significant value against the pickleworm when used with 
cryolite in 1949 and tended to be so in 1950 (table 3). However, it was 
of no significant value against the pickleworm when used with cryolite 
or rotenone in 1948 (table 3), or when added to rotenone, sabadilla, or 
pyrethrum in 1950 or to sabadilla and allethrin in 1951 (table 3). 

Dusts containing 1 percent of nicotine and 4 percent of either poly- 
ethylene glycol (600) monolaurate or bis(p-chlorophenyl) sulfide^/ were 
ineffective against the pickleworm on squash and on cucumbers (table 3) 
in 1951. Cucumber plants receiving these dusts had significantly higher 
melon aphid infestations than did untreated plants (table 5). The first 
mixture caused slight injury, and the second mixture caused severe 
injury and a reduction in yield. A dust containing 0.5 percent of 



2/ These mixtures were supplied by the Bureau of Agricultural and 
Industrial Chemistry. 



- 14 



ni en1 of polyethylene glycol (600) monolaurate and 20 per- 

cent adequate control of the pickleworm in 1951 

(tal 

P irathion 

P on was among the most effective materials tested, but was 

h extei: !s as lindane, DD'I, i ryolite, and methox 

chlor. It gave good control of the melonworm and the melon aphid in 

18, and of the mel< 1951 (table 5). Parathion was less 

ef than gamma BHC and lindane against the pickleworm, when 

used as 1 -percent dusts (tables 3 and 4). A 0.5-percent parathion dust 

inferior to a 0.5-percent lindane dust against the pickleworm in 
1951 (table 3). The residual effect of parathion against this insect did 
not appear to be so lasting as that of lindane, cryolite, and DD'I . 1 
itions of a 1- percent parathion dust at intervals of 7 to 8 days 
gave almost adequate protection to cucumbers against a heavy pickle- 
worm infestation in 1949; four applications of a 0.045-percent parathion 
suspension gave excellent i i that season (table 3). Similar use of 

a 1 -percent dust provided adequate control of the lighter infestation. 1 - 
ntings being treated with zineb in 1950 (table 4) and 1951 (table 3). 
1 his insecticide showed no phytotox to cucumbers even though in 

1950 as many as seven applications of a 1 -percent dust nade, 

beginning when the plants had only one to three true leaves. 

A spray containing 0.028 pi ■ , a proo mtaining 

methyl parathion and parathion, was among the least effei atenals 

used against th< orm in e nent 1 >0, and did not 

provide adequate control of this insect (table 3). 

P ' hrum 

p. ■ ethrum dusts showed a high degree of t. s 

In I e tests. An impri ted 0.4- 1 - dust 

kill of all 'f the pickleworm in I An 

thrift Fifth-ii 

. . a t killed all Fourth In 

he fifth ii . ."• tly fr 

em the 0, 

ercent 
■ 
Whei 

r 
: , and 



- 15 - 



Q-137 

In laboratory cage tests in 1950, average and heavy dosages of a 
dust containing 3 percent of Q-137 showed only moderate toxicity to 
third- and fourth-instar pickleworms. A 5-percent dust was one of the 
least effective insecticides used on field plots in experiment 1 of 1950, 
but gave almost adequate control of the light pickleworm infestation 
(table 3). Q-137 showed no phytotoxicity to cucumbers. 

Rotenone 

Insecticides containing rotenone showed little toxicity to fifth-instar 
pickleworms in laboratory cage tests. A 1 -percent rotenone dust killed 
only 20 percent of these larvae; a 2-percent dust killed 70 percent. The 
effectiveness of a 1 -percent rotenone dust was not appreciably increased 
by addition of 1 percent of either piperonyl butoxide or compound 469. 

One-percent rotenone dusts did not give adequate control of the 
pickleworm in field tests (table 3), even though in 1951 they were 
preceded by lindane and accompanied by zineb. During the fruiting 
period of cucumber growth in 1950, populations were too low for the 
value of 1.5- and 2-percent rotenone dusts to be determined. Addition 
of piperonyl cyclonene, n-propyl isome, nicotine, or mineral oil did 
not significantly increase the toxicity of a 1 -percent rotenone dust in 
1948 and 1949 (table 3). A dust containing 0.15 percent of pyrethrins 
and 0.5 percent of rotenone was ineffective on cucumbers in 1948. 

Ryania 

A dust containing 40 percent of ryania did not give adequate control 
of the pickleworm in 1948 and 1949 (table 3). 

Sabadilla 

A 20-percent sabadilla dust did not provide adequate protection 
against the pickleworm, but this dust tended to be slightly more effec- 
tive than rotenone, pyrethrum, allethrin, and ryania dusts (table 3). 
Addition of 0.5 percent of nicotine plus 2 percent of polyethylene glycol 
(600) monolaurate did not significantly increase its effectiveness in 1951. 
In the 1950 planting the pickleworm infestation was too low for the value 
of a 25 -percent sabadilla dust, with and without piperonyl butoxide and 
nicotine, to be determined. 






I DE 

IDE dust was one of tl als used 

ainst tl .ment 1 of 1950 (table 3). It was inferior 

to .me dust, and c aused moderate chlorosis of cucumber 

foi 

soprop) I Pj :• ohosphate 

lisopropyl pyrophosphate dust was of no apparent 
value against the pi< kl-worm in experiment 1 of 1949 (table 3), and 
gave only 53 -p< »n of th< onworm in tl ar. 1 

ed no not iant injur . 

Effect of Zineb on th< I .vorm 

During the 1950 studies considerable evidence was obtained to sub- 
stantiate the observations of Genung (12) that the fungicide zineb is 
moderately toxic to the | worm. The unusually low pickleworm 

Station on cucumbers in the Charleston, S.C., area in the fall of 
that year was attributed at least partly to the extensive use, for the first 
time, of for disease control. Additional evidence of the tc of 

zineb to the pickleworm was obtained i . eral laboratory cage tests 

and a small-s« -Id-plot experiment on squash (Reid 18). 

[n experiment 3 of 1951 (table 3) two 4-percent zineb dusts prepared 
from dif: ercial brands of that fill le significantly reduced 

the number of pickleworm -infested cucumbers, but did no: quate 

protection. Both dusts caused si hlorosis of the foliage and also a 

significant increase in the melon aphid population (table 

Th- trol of the pit h i m with si pron 

195 taking possil thai inse> dos- 

s of lii »ed, tl r of 

lue, off-i ' I ■ • I 

ilent ; i rs 

pickleworm lnf< 51 

anied by weekly appli 
plantinj 

pp] Led .i week I the I 

aln 

A dust containinj en1 

ethi teatii 

ethrum 



17- 



RESIDUE STUDIES 

Representative samples of cucumbers from plants treated with 
certain insecticides shortly before or during the fruiting period, or at 
both times, were collected in 1948 and 1949 by W. J. Barbour, resident 
inspector of the Food and Drug Administration, and sent to the Atlanta, 
Ga., office for residue determinations. Similar samples were furnished 
the Division of Insecticide Investigations of this Bureau in 1950. The 
cucumbers were of slicing size, averaging about 2 l/4 inches in diameter 
and 0.65 pound in weight. Some of the 1948 samples were run through a 
brushing and waxing machine, and some of the 1949 samples through a 
more elaborate washing, waxing, and polishing machine. The treat- 
ments of the various samples and the findings of the chemists are shown 
in table 6. 

The quantity of residue from the different insecticides and from 
different samples of certain insecticides varied considerably. The only 
residues of appreciable quantity were those that followed the use of 
gamma BHC in the fall of 1948 during the fruiting period, and of cryolite 
in the spring of 1949. Similar applications of gamma BHC in the spring 
of 1949 and of lindane in the falls of 1949 and 1950 apparently resulted 
in little or no residue at time of harvest. Cryolite residues were rather 
variable and sometimes as high as 82 p. p.m. of fluorine. It is not under- 
stood why plants that received the last cryolite application on May 23, 
1949, before the fruits appeared on the plants, produced fruits showing 
9.6 p. p.m. of fluorine. A control program in which lindane was used 
during the prefruiting period and cryolite thereafter resulted in residues 
of 0.6 p. p.m. of gamma BHC and 2 p. p.m. of fluorine. The fluorine 
residue was reduced to 0.2 p. p.m. by washing and waxing of the fruits. 
DDT, parathion, and methoxychlor residues were low, even when these 
materials were applied on the day of harvest. The lindane and cryolite 
residues were reduced as much as 80 to 90 percent by commercial 
brushing (or washing) and waxing machines. These machines may not 
have reduced the residues to safe levels, however, Similar findings 
for cryolite have been reported by Fulton (11). 

SUMMARY 

The pickleworm (Diaphania nitidalis (Stoll)) and the melonworm 
( Diaphania hyalinata (L.)) are serious pests of fall crops of squash and 
cucumber in the South Atlantic and Gulf States. They also frequently 
cause damage in adjoining States and occasionally as far north as 
Illinois and Connecticut. These insects spread northward each spring 
and summer from semitropical areas. The melon aphid ( Aphis gossypii 
Glov.) and several species of cucumber beetles cause damage to cucurbit 
crops at times. 



- 18- 



10 and 1934 J that adequate 

prot( and a fair -of control of 

picl Id be obtained by frequent applications of lead arsen. 

, or barium fluosilic . • I .m 

i is green, 'irum, and rotenone usually were less 

.iinst the pickli Sulfur proved to be of considerable 

,ie as a funj; an insecticide in the dust 

mixtur • 

[i 1948 Laboratory i age and field-plot i .merits were undertaken 

to develop i. rfective and safer measures for the control of the 

i associated insects. Lindane was the most ve 

givei sive trial. A 1 -percent lindane dust applied w 

at the rate of about 20 pounds per acre, or s iing a com- 

lent < ontrol of all insects present on <. ucumbers 

; squash. I here were indications, however, that the use of lindane 
during the fruiting period may impart a slight off-flavor or off-odor to 
• s, and that .eties of Irish potatoes may be similar 

immediately follows lihdane-treab 
\> hough tested less exten than lindane, proved o: 

slightly less ef: ■ against the pick m and as lindane 

to the melon aphid and the other insects. A purified grade of DDT us 

. ed inferior to lindane but superior to cryolite against the pickleworm. 
marked increase in the melon aphi lation often follov. 

the use of DDT an Aldnn, dieldrin, and endrin she »- 

siderable promise against both insects in limited tr 

Mes th 1 less effect Inst the pickleworm 

Ch] ilor, CS-674A, C'S , tetl sopro; 

I Ul , 7, h« and n: is 

nyl) sulfi( ono~ 

lai. 

Lethrin, and 

■ 

MX 



- 19 - 



DDT dusts (both grades) and of TDE, methoxychlor, chlordane, endrin, 
zineb, and nicotine plus polyethylene glycol (600) monolaurate. 

Insecticide residues as high as 12.2 and 82 p. p.m., respectively, 
were found on cucumbers when gamma BHC and cryolite were applied 
weekly until the day of harvest. These residues were reduced to 7.7 
and 16.2 p. p.m., by a commercial brushing or washing machine. Residues 
that followed similar use of lindane, purified DDT, parathion, and 
methoxychlor were not more than 1.6 p. p.m. 

LITERATURE CITED 

(l)Alban, E. K., and Keirns, V. E. 

1948. The effect of rotenone, commercial, and aerosol grade 
DDT dusts on the total yield, grade, and maturity of 
seven cucurbit varieties. Amer. Soc. Hort. Sci. 
Proc. 51: 448-452. 

(2) Anderson, Lauren D., and Hofmaster, Richard N. 

1948. Control of pickleworms on cucumbers and cantaloupes. 
Jour. Econ. Ent. 41: 334-335. 

(3) Arant, F. S. 

1940. A progress report on the use of rotenone dusts for the con- 
trol of the pickleworm and the melonworm in Alabama. 
Jour. Econ. Ent. 33: 840-843. 

(4) 



1941. Rate of application of derris-talc dusts for pickleworm 
control. Jour. Econ. Ent. 34: 520-521. 



(5) 



1942. Effectiveness of derris and cube in pickleworm control. 
Jour. Econ. Ent. 35: 870-872. 



(6) Brooks, James W., and Anderson, Lauren D. 

1947. Toxicity tests of some new insecticides. Jour. Econ. Ent. 

40: 220-228. 

(7) Carruth, L. A., and Howe, W. L. 

1948. Factors affecting use and phytotoxicity of DDT and other 

insecticides for squash borer control. Jour. Econ. 
Ent. 41: 352-355. 

(8) Crowell, H. H., and Morrison, H. E. 

1950. The phytotoxicity to cucurbits of some new insecticides. 
Jour. Econ. Ent. 43: 14-16. 






) Dupi , V id Beckham, C. M 

ie tests for control of pickle- 
worm 

, 8 pp. 

( 10) Fulton, B. B. 

17, B ontrol of the p. >rm. . Agr. Expt. 

Sta. I . .1. 85, :>. 

(11) Genung, William G. 

Dithane dust indicates effective control of melon worm and 
pickle worm. Fla. State Hort. Soc. Proc. 62: 130-132. 

(12) Kelsheimer, E. G. 

1949. Control of insect pests of cucumber and squash. Fla. Agr. 
Expt. Sta. Bui. : 5 pp. 

(13) Kirkpatrick, M E., Mountjoy, Beatrice M., Albright, Linda 

Poos, Fred W., and Weigel, Charles A. 

1951. Flavor and odor of cooked potatoes as affected 1 of 

lindane and benzene hexachloride as insecticides. 
Amer. Potato Jour. 28: 792-799. 

(14) Mitthewman, W. G., Harcourt, D. G., ( .ss, L. M., and Friend, 

G. 

195'. Iht .,1 reactions of i nd metho 

chlor dust. Canad. Ent. 82: 102-111. 

(15, , . L . 

1899. S lies o: irbits. (, . pt. 

Sta. ] ; , pp. 36-41. 

6) 



1901 . I he pi. . Expt. Sta. , p. 

(17) Reid, \\ . J., Jr. 

LTbami ind 

.Ent, 818. 

•i, K. 1. 

: 



1911, Tv. 

Bui. a , 



- 21 



(20) Sullivan, K. C. 

1924. The pickleworm and its control. Mo. Agr. Expt. Sta. 
Cir. 122, 4 pp. 

(21) Watts, J. G. 

1939. Insect control investigations - The pickleworm. S. C. 
Agr. Expt Sta. A. R. 521, pp. 189-193. 

(22) White, W. H. 

1937. Recommendations for the control of insects attacking 

certain vegetables, small fruits, and tobacco. U.S. 
Bur. Ent. and Plant Quar. E-376, 14 pp. 



- 22 - 



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ca 

x 
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3 
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E 
a 

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m onfall < ucumbt th various in i ies. 

All i dust 



1 1 . de 

: 



dosage 

icre 



All 
harv« 









ible 
cue 

acre 



Number Percent Bushels 



, is at 7 


- to 


■ i 


Is) 




Gamn 1 


19 pou 


nds 




10 




. 


18 




37 




13 


P rathion l 


18 




36 


18 


13 


DDT 3 


17 






56 


8 


3 (purified) 


18 




22 


60 


8 


1 plus pyrethrins >th impregnated) 


20 




: 


30 


2 


1 (impregna* 


19 




20 


31 


: 


1 


20 




16 


67 


5 


• olite 50 plus nicotine 1 


18 




23 


51 


9 


50 


20 




19 


56 


7 


hoxychlor 5 


19 




15 


53 


5 


Rotenone 1 


17 




13 


65 


i 


Chlordane 2 
L< ' significant difference at odds of 19:1 


22 




9 


1 -^ 


3 








1 1 . %j 




99:1 








1.1 





1948, K ent 3 (3 applications at 7 -da 3 intervals) 



: Hi ' 1 

d powd< • 
1 powd< 
1 ' rethrins 0, 

i plus • 
■ 

1 plu 1 

1 plus oil-', 2 
oil-* 1 

1 

. 

1 

i mt diff( 



25 

27 
31 
30 



3' 


• 


306 




. 




309 


28 


313 








2« c 


36 






70 


38 


(0 


















- 1 . 




. 



69 
56 
63 

63 

51 






1/ 1! 

boll 1 ., 



- 25 



Table 3. --Continued 



Insecticide 
(figures indicate percent) 



Average 

dosage 

per acre 



All cucumbers 
harvested 



Sound 



Wormy 



Marketable 

cucumbers 

per acre 



Number Percent Bushels 



1949, Experiment 1 (5 applications at 7- to 8-day intervals) 



Parathion 1 

Aldrin 2.5 

CS-708 3 

CS-674A 2 

Cryolite 50 plus nicotine 2 and lime 5 

50 
CS-645A 2 

Methoxychlor 2.5 (impregnated) 
Tetraisopropyl pyrophosphate 1 
Untreated 
Least significant difference at odds of 19:1 

99:1 



23 pounds 473 



22 
23 
22 
21 
22 
23 
22 
22 



503 
380 
354 
297 
224 
187 
130 

52 

45 

78.7 
105.1 



10 
15 
32 
34 
36 
47 
52 
64 
77 
74 

9.7 
13.0 



1949, Experiment 3 (4 applications at 6- to 10-day intervals) 



Parathion 0.045 (suspension spray) 
CS-645A 0.094 (emulsion spray) 
Methoxychlor 0.181 (suspension spray) 

.189 (emulsion spray) 
Untreated 



66 gallons 246 
66 218 

66 48 

66 34 

15 



Least significant difference at odds of 19:1 ------- 93.5 

99:1 131.1 

Lindane 0.047 (emulsion spray) 66 233 

1949, Experiment 4 (4 applications at 6- to 7-day intervals) 

Sabadilla seed powder 20 
Pyrethrins 1 

0.3 plus piperonyl cyclonene 1 
.3 plus n-propyl isome 1 
.3 
Rotenone 1 plus piperonyl cyclonene 1 
1 plus n-propyl isome 1 
1 
Ryania 40 
Untreated 
Least significant difference at odds of 19:1 

99:1 



134 
151 
119 
104 

97 

80 

66 

46 

19 

17 

34.1 

45.6 



0.8 


107 


4 


96 


75 


16 


77 


14 


89 


6 


27.9 


60.5 


39.2 


84.9 


2 


194 



26 pounds 


349 


34 


125 


27 


406 


35 


141 


27 


313 


44 


112 


26 


295 


44 


112 


27 


292 


46 


103 


25 


332 


45 


117 


25 


285 


46 


96 


25 


322 


44 


116 


26 


275 


44 


103 


_ 


182 


56 


69 






Q 9 


24.8 
33.1 






- 13.3 



26 



ued 









All c 

■ 



Sound 






re 



, E nt 1 (4 appli. to 8->. . als) 



Ldrin 

•'ray) 
1 
.5 
Aldr 

Hepta< hlor 0.24 (susp< n spra 

CS 

. 

JO plus ni e 5 

70 
E 3 

hoxychlor 10 
37 5 

n spr. 

east s. .nt difJ 

ui 1 plot Ids of 1 9: 1 - 

1:1 

I 
urr • - - - 

1:1 



8 43 
allons 1,059 
22 pounds 

901 
951 

gallons 892 

pounds 

ions 909 

rounds 

800 
852 
867 
787 

gallons 831 
648 



• 




' 







265 


. 


333 












286 




268 


.6 




.6 




.8 






256 




264 


. 




. 




. 




. 






48. 


. 


64.8 


• 1. 









. als) 



25 plus ; 

. 
25 pi 
1 • ins ( Lmpregn it. 

.2 plus Lin ... 

• lws ni .30 

.... om| 

. 

. l 



nds 8 






891 














4 






1 























2J A 



27 



Table 3. --Continued 



Insecticide 
(figures indicate percent) 



Average 

dosage 

per acre 



All cucumbers 
harvested 



Sound 



Wormy 



Marketable 

cucumbers 

per acre 



Number Percent Bushels 



1950, Experiment 3 (continued) 



Pyrethrins (impregnated) 0.075 plus rotenone 
0.375 and piperonyl cyclonene 
0.75 
Rotenone 2 

1.5 

1.5 plus nicotine 2.5 
Allethrin 1 

1 plus piperonyl butoxide 1 
Untreated 
Least significant difference at odds of 19:1 



1951, Experiment 1 (5 applications at 5- to 10-day intervals) 



25 pounds 


823 


4 


255 


26 


982 


2 


315 


26 


845 


2 


252 


26 


919 


2 


284 


28 


808 


2 


264 


24 


781 


3 


248 


- 


.798 


6 / 

3/ 

- ns— 


257 



Lindane I , 20 
1-3 21 


773 







190 


856 


0. 


1 


194 


0.5 20 


852 


o 


9 


194 


Cryolite 50 21 


639 


5 




137 


DDT 2 (purified) 20 


737 


5 




169 


Parathion 0.5 20 


827 


9 




196 


Untreated 


405 


37 




108 


Least significant difference at odds of 19:1 - - - - - 




- 3. 


5 


34.7 


99:1 




- 4. 


7 


46.7 



1951, Experiment 2 (1 application) 



Sabadilla 20 

20 plus nicotine 0.5 and poly- 
ethylene glycol (600) 
monolaurate 2 
Pyrethrins (impregnated) 0.15 

.1 
.1 plus lindane 0.25 

.1 plus piperonyl 
butoxide 1 



36 



25 



3/ Data not significant according to the F test. 
A[ Four applications. 



541 



450 



20 



28 



173 



29 


536 


14 


172 


25 


472 


30 


162 


25 


449 


31 


158 


27 


632 


10 


185 



151 






. 











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31 














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608 






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618 






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89 


























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33 



Table 5. --Infestations of the melon aphid on fall cucumbers treated with 
several insecticides for pickleworm control, 1951. All insecticides 
applied as dusts unless otherwise indicated. 



Insecticide 
(figures indicate percent) 



Average 

dosage 

per acre 



Melon aphid 
index rating—' 



Count 1 



Counts 
1 and 2 



Pounds 



Experiment 1 (5 applications at 5- to 10-day intervals 



Parathion 0.5 
Lindane 1 (4 applications) 
1 

0.5 
DDT 2 (purified) 
Cryolite 50 
Untreated 
Least significant difference at odds of 19:1 

99:1 



20 
21 
20 
20 
20 
21 






3 


8 


25 


5 


32 


16 


44 


78 


221 


247 


701 


40 


108 


53.1 


100.5 


71.5 


135.4 



Experiment 3 (3 applications at 10- to 13-day intervals) 



Dieldrin 2.5 


25 


Endrin 1 


23 


Lindane 1 


22 


0.5 


22 


Aldrin 2.5 


23 


Heptachlor 2.5 


22 


Methoxychlor 10 


21 


CS-708 2 


21 


Nicotine 1 plus bis(p-chlorophenyl) sulfide 4 


24 


1 plus polyethylene glycol (600) 




monolaurate 4 


23 


Zineb 4, product B 


22 


product A 


22 



Lindane 0.025 (emulsion spray) 
Untreated 
Least significant difference at odds of 19:1 

99:1 



Gallons 
45 



8 


25 


5 


37 


9 


50 


17 


77 


23 


65 


38 


268 


201 


597 


313 


997 


293 


1,025 


304 


1,082 


336 


822 


357 


1,165 


16 


79 


130 


745 


141.4 


345.2 


188.6 


460.4 



l/ Counts were made 1 week apart during the middle of the harvesting 
period. 



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